The present invention relates to a method of riveting a headed fastener. In the prior art, it is known to provide a tee nut with a counterbore that makes it easier to rivet the tee nut either over a surface of a material or within a hole formed therethrough. Counterbored tee nuts have been known since as long ago as the late 1980s. A counterbored tee nut with a circular flange has been marketed since at least as early as 1988. In 1992, a counterbored tee nut having an octagonal flange was developed by Sigma Tool and Machine. U.S. Pat. No. 5,348,432 also discloses a counterbored tee nut having an octagonal flange. Recently, a patent application was filed disclosing and claiming a square-headed fastener having a shaft with a counterbore intended to be riveted. That application was assigned Ser. No. 10/105,248 and was filed on Mar. 26, 2002.
Typically, tee nuts are flared, whether fully threaded or counterbored, using an anvil and a flaring pin. The flaring pin enters the end of the shaft at an opening distal from the flange and flares the end radially outwardly with respect to an axis of elongation of the shaft. In some cases, when the shaft end is flared, discontinuities are formed about the circumference of the flared portion, although the locations of such discontinuities may not be accurately predicted.
Often, tee nuts that are flared have a flange with pawls or other ribs or projections extending in the same direction of elongation as that of the shaft so that they embed in the surface of the material through which the shaft extends to preclude the shaft from rotating when a threaded fastener is inserted therein. Often, these pawls, ribs or other projections are insufficient to preclude xe2x80x9cspin-outxe2x80x9d of the shaft when the fastener is inserted and rotated. The flared portion of the shaft is designed solely to preclude the tee nut from being pushed out of the material in which it has been installed. The present invention contemplates enhancing the function of the flared portion of a tee nut shaft so that it performs dual functions, (1) preventing push out, and (2) precluding xe2x80x9cspin-outxe2x80x9d of the shaft during fastener insertion.
The present invention relates to a method of riveting a headed fastener. The present invention includes the following interrelated objects, aspects and features:
(1) The present invention is intended to be used in association with a headed fastener such as a tee nut, but not limited to a tee nut. The present invention is equally usable on counterbored tee nuts as well as those that are fully threaded.
(2) In practicing the teachings of the inventive method, the present invention contemplates embodiments of a riveting pin having protuberances that cause the flared end of the shaft to be flared in one or more discontinuous portions of the circumference of the shaft. In the case of riveting, where the length of the shaft is greater than the thickness of the material through which it extends, the flared discontinuous portions or tangs are of two types, one type that digs into the top surface of the material and a second type that digs into the inner walls of the passage or hole through which the shaft extends. Each type deters xe2x80x9cpush outxe2x80x9d and xe2x80x9cspin-out.xe2x80x9d Where the shaft is of a length equal to or less than the thickness of the material through which it extends, the discontinuous portion or portions dig into the walls of the passage or hole through which the shaft extends to deter xe2x80x9cpush outxe2x80x9d and xe2x80x9cspin-out.xe2x80x9d
(3) In explaining the teachings of the present invention, the fastener which is disclosed as an example is a square-headed rivet fastener such as is disclosed in co-pending application Ser. No. 10/105,248. That fastener is counterbored and has a square flange with eight ribs extending upwardly from a top surface of the flange.
(4) Where the length of the fastener shaft is no longer than the thickness of the material through which it is inserted, a first design of flaring pin is provided. Where the length of the shaft of the fastener employed is greater than the thickness of the material through which it extends, a second embodiment of flaring pin is employed. In the former case, in order for the present invention to work, it is only necessary for one discrete portion of the circumference of the shaft to be flared into the wall of the passageway through which the shaft extends. In the latter case, for the invention to operate as intended, it is only necessary for one portion of the circumference of the shaft to enter the wall of the passageway and one other portion of the circumference of the shaft to be folded over and embedded into the exterior surface of the material.
(5) While the fastener example shown in this application is a square-headed rivet fastener, the teachings of the present invention are equally applicable to other kinds of fasteners having a shaft and a flange where the shaft is either fully threaded or counterbored.
As such, it is a first object of the present invention to provide a method of riveting a headed fastener.
It is a further object of the present invention to rivet a fastener comprising a tee nut.
It is a yet further object of the present invention to provide a method of riveting a fastener having any style flange so long as the shaft is elongated and hollow, whether or not counterbored.
It is a yet further object of the present invention to provide such a method applicable to a fastener having a flange and an elongated fully threaded shaft.
It is a still further object of the present invention to provide such a method in which a portion of the circumference of the shaft is bent and forced into a wall of a passageway through which the shaft extends.
It is a still further object of the present invention to provide such a method in which one portion of the shaft is bent and forced into the wall of the passageway through which the shaft extends and another portion of the circumference of the shaft is bent over an outer surface of the material.
These and other objects, aspects and features of the present invention will be better understood from the following detailed description of the preferred embodiments when read in conjunction with the appended drawing figures.